Characterisation of materials for organic photovoltaics

View/Open

Date

Author

Supervisor

Keywords

Metadata

Abstract

Organic solar cells offer the possibility for lightweight,
flexible, and inexpensive photovoltaic devices. This thesis
studies the physics of a wide range of materials designed for use
in organic solar cells. The materials investigated include
conjugated polymers, conjugated dendrimers, and inorganic
nanocrystals.
The materials studied in this thesis fall into five categories:
conjugated polymers blended with a buckminsterfullerene derivative
PCBM, nanocrystals synthesised in a conjugated polymer matrix,
conjugated polymers designed for intramolecular charge separation,
conjugated dendrimers blended with PCBM, and nanocrystals
synthesised in a matrix of conjugated small molecules or dendrimers.
Conjugated polymers blended with PCBM have been extensively
studied for photovoltaic applications, and hence form an ideal
test bed for new experiments. In this thesis this blend was used
to achieve the first pulsed electrically detected magnetic
resonance experiments on organic solar cells.
Nanocrystals are attractive for photovoltaics because it is
possible to tune their band gap across the solar spectrum. In this
thesis a one-pot synthesis is used to grow PbS and CdS
nanocrystals in conjugated polymers, soluble small molecules, and
dendrimers, and characterisation is performed on these composites.
Previous work on dendrimer: nanocrystal composites has been
limited to non-conjugated molecules, and the synthesis developed
in this thesis extends this work to a conjugated oligomer and a
conjugated dendrimer. This synthesis can potentially be extended
to a variety of conjugated soluble small molecule: nanocrystal and
dendrimer: nanocrystal systems.
Conjugated dendrimers have been successfully employed in organic
light emitting diodes, and in this thesis they are applied to
organic solar cells. Materials based on fluorene and cyanine dye
cores show excellent absorption tunability across the solar
spectrum.
A set of electronically asymetric polymers designed for
intramolecular charge separation were investigated. Quenching of
the luminescence was observed, and light induced electron
paramagnetic resonance measurements revealed that photoexcitation
led to approximately equal numbers of positive polarons and nitro
centred radical anions. This indicates that charge separation is
occurring in these molecules.

Electronic thesis deposit

Repository help

Cookie policy

We may use a cookie file which is stored on the hard drive of your computer to track how the Site is being used and to assess its usefulness. Personal information is not collected. Terms and Conditions.